Accelerating Industrial Biotechnology
Biobased chemicals and polymers derived from corn or wood or a hundred other biomasses are highly touted as potential game-changers in the chemicals sector. Through the years, many of the prominent initiatives in biobased chemicals and polymers, such as NatureWorks’ polylactic acid and DuPont Tate & Lyle’s 1,3 propanediol, relied on industrial biotechnology platforms like fermentation or biocatalytic techniques as springboards to bring their products to market.
Building on those successes, several chemical companies are employing novel chemocatalytic approaches via high-throughput screening (HTS) experimentation as a tool to help them identify catalysts to make new intermediate and platform chemicals from biomass. HTS experimentation involves sophisticated robotics, data processing and control software, liquid handling devices and sensitive detectors for chemists to rapidly conduct hundreds, thousands or even millions of biochemical screening experiments.
One firm that actively uses HTS experimentation methods in its technology platform is Amsterdam-based Avantium, which also provides high-throughput equipment and services for chemical and pharmaceutical clients. Specifically, the biochemical producer uses a parallel catalyst testing platform called Nanoflow for its catalyst development work. The company inherited the basis of the technology from oil conglomerate Royal Dutch Shell, from which Avantium was formed. It subsequently advanced the technology and developed several proprietary features to enable the testing of heterogeneous catalysts under industrial conditions. The use of its Nanoflow technology, according to Chief Technology Officer Gert-Jan Gruter, allows the company to run many experiments within its 64 fixed-bed lab-scale reactors as effectively and economically as petrochemical platforms.
“By using a chemocatalytic route we can keep all the six carbons in the product,” Gruter tells Biorefining. “You can generally optimize and fine-tune these heterogeneous catalysts relatively easily compared to genetically modifying enzymes.”
The use of HTS in its technology platform has been essential to Avantium’s goals of creating a biobased alternative to petroleum-derived polyethylene terephthalate (PET) by using biobased ethylene glycol, and replacing purified terephthalic acid (PTA) with its platform chemical 2,5-furandicarboxylic acid (FDCA). According to a 2004 U.S. DOE report, FDCA was listed as one of the top 12 biobased building blocks.
As a way to get to FDCA, however, a bifunctional furan is needed as an intermediate. Traditionally, chemists have gotten the sugar molecule hydroxymethylfurfural (HMF) as a primary product. But HMF has its drawbacks, according to Gruter. “The problem with HMF is that, under the conditions where it’s formed, the acidic conditions in the presence of water, HMF reacts further to form levulinic acid,” he says. “It cannot be isolated easily. It also dissolves quite well in water and it cannot be distilled easily, so it’s not an ideal target to work on.”
Gruter credits the company’s Nanoflow technology for coming up with a catalyst to make methoxymethylfurfural (MMF), a stable alternative to HMF from glucose and fructose. This has allowed Avantium to oxidize MMF to make FDCA, Gruter says. “Essentially, we have a primary step where we convert the sugars to HMF derivates, like MMF, and then in the second step we can either convert them into furan-based fuel components or into FDCA as chemical building blocks to potentially replace terephthalic acid used to make PET.”
Avantium calls its furanic chemistry platform “YXY.” The company has teamed with NatureWorks to help commercialize its furanics along with NatureWorks’ parent company, Cargill Inc., for access to starch-based sources such as syrups. The company started construction of a pilot plant in October to produce its furanics-based monomers and polymers beginning early next year. Gruter says Avantium also intends to use lignocellulosic biomass feedstock, where economically and technically feasible.
Eyeing Adipic Acid
While Avantium uses HTS to accelerate its furanic-based chemistry for biobased chemicals and fuels, Menlo Park, Calif.-based Rennovia Inc. is working to utilize its HTS capabilities to develop chemocatalytic methods to produce existing major chemicals. One chemical Rennovia is focused on is adipic acid, which represents a 4.8 billion pound global market, according to Chemical Market Associates Inc. Adipic acid is a monomer used to manufacture nylon 6,6 fibers and resins, adipate esters and polyurethanes. The per-pound selling price for adipic acid is about $1.25, according to ICIS Chemical Pricing.
Unlike adipic acid produced from cyclohexane feedstock by petrochemical refiners, Rennovia’s chemocatalytic process uses glucose, which is converted into a glucarate intermediate via catalytic oxidation. The glucaric acid is then converted into adipic acid using a selective hydrogenation process with water as a byproduct.
There are other companies that have identified adipic acid’s market potential, but Rennovia CEO Bob Wedinger says he believes his company is the first to use a chemocatayltic pathway via HTS experimentation. The company believes that high space-time yields, temperature, solvent flexibility, high carbon efficiencies and low costs of product isolation are technical characteristics that make chemocatalysis the preferred method over fermentation-based techniques for high-volume chemical production, Wedinger says.
“If you’re doing fermentation, you have to keep the bugs alive” he says, adding that employing chemocatalysis methods can be more readily used in existing petrochemical assets than fermentative approaches. “We have a lot more flexibility where we can run at higher pressures, high or lower temperatures, pH flexibility and so forth. It gives us more degrees of freedom.”
Based on this knowledge, Rennovia developed its own structure for high-throughput R&D into catalysts that can automatically synthesize and screen about 2,000 catalyst formulations per week using HTS experimentation, according to Wedinger. The company exploits its high-throughput expertise to compress the time and cost of early-stage catalyst discovery, and to develop and establish broad intellectual property coverage around its platform technologies.
The chemical catalysis used in the two later stages of Rennovia’s adipic acid technology were developed by Rennovia's founders, Tom Boussie and Vince Murphy, who were formerly with Symyx Technologies, a company in the field of high-throughput technology for catalyst, and other chemicals and materials, development.
Wedinger believes that adapting traditional petrochemical processes for renewable feedstock conversion is the fastest, lowest risk and the most cost-effective path to successful commercial adoption. “The further away from the refinery we get, the better advantage we have versus the existing petrochemical processes,” Wedinger says. “That’s why we chose product targets like adipic acid, where we’ll have a significant cost advantage.”
Wedinger says the company plans to move out of lab-pilot stage with demonstration-scale development expected by 2012 with a commercial plant by 2014. The firm also intends to use existing infrastructure for its feedstock supply, including tapping into the oversupplied high-fructose corn syrup capacity.
Getting to Glucaric Acid
While it may not utilize HTS experimentation like Avantium and Rennovia, Rivertop Renewables leverages a different approach to making its glucaric acid from glucose. Based on 10 years of research that began at the University of Montana, Rivertop Renewables employs a proprietary process that utilizes nitric acid ito oxidize sugars wihtin a catalytic process, according to Tyler Smith, the company’s research and development director.
“Ultimately, we’re consuming oxygen and glucose so, from that standpoint, it’s a catalytic process,” he says, adding that the oxidation platform is adaptable to feedstock beyond glucose, such as sucrose and xylose. “We’re not screening hundreds of different catalysts or anything like that. That’s not our game.”
In addition to glucaric acid, the company is also investigating xylaric, arabinaric and mannaric acids, which are derived from sugars extracted from woody biomass, to make a range of bioproducts and polymers. Early markets for its glucaric acid include being used as a substitute for phosphates in detergents, corrosion inhibitors for road salt deicers and a sequestering agent for a wide variety of metals. The company, according to Smith, sees its glucaric acid being a viable replacement to phosphates in detergents alone, representing a $10 billion market opportunity.
“One of the attractive points to our technology is that it’s scalable and capital efficient,” Smith says. “A lot of people might look at our chemistry and say, ‘Well that’s not as sexy as some of the other chemistry,’ or maybe not as high-tech, but it’s really about keeping it simple and getting the cost down to make it scalable.”
Rivertop has tripled the size of its lab-scale reactor and plans to build a pilot plant with an annual capacity of about 100,000 pounds, according to Smith.
Although companies like Avantium and Rennovia see chemocatalysis holding an edge over biotechnological platforms, the companies don’t dispute how far industrial biotechnology has evolved over the years. In fact, companies like these are exploring the ability of chemical catalysis to assist and even expand the chemistry of biocatalysis. Incorporating biocatalytic and chemocatalytic steps into a reaction cascade could mimic biochemical pathways and enable value-added products to come out of one stream.
Wedinger expects industrial biotechnology and chemocatalytic processes to coexist and even complement each other—enzymatic technology could be used to free up sugars and then, once those sugars are available, companies like Rennovia could step in and chemically convert them.
“There are some chemicals that will be more cost-effective to get from fermentation, and there are some chemicals that are more cost-effective from chemocatalysis,” he says. “If there’s a raw material that’s derived from fermentation that’s a cost-effective route, and we take that and do further transformations on it, that’s fine.”
Gruter echoes Wedinger’s sentiments. “We think converting polymeric carbohydrates like lignocelluloses, cellulose and hemicelluloses in that first step is where biocatalytic technology could play an important role,” he says. “The first step could be biotechnology and the second step could be to use our chemocatalysis route, which makes sense if you want to make chemicals or furan-based fuels.”
Author: Bryan Sims
Associate Editor, Biorefining